问题补充：
---Must we donate our pocket money to the poor right now?
---No, you . You can think it over and do it before Friday.
A. mustn’t
B. needn’t
C. can’t
D. couldn’t
答案：
A. mustn’t
(答案→)B. needn’t
C. can’t
D. couldn’t
解析：考查must的否定回答.must含义是必须,一定;mustn’t含义是禁止.故must的否定回答,一般借助于needn’t和don’t have to,结合前文no,可知本句为否定回答.结合所给选项,可知选B.
